[ch3mgirl]

A 4.00L gas sample initially at -10.0 degrees Celsius is heated to 40.0 degrees Celsius and the volume expands to 5.00L. What was the change in pressure?

I thought you needed at least one pressure point.
So I have:
V1 = 4.00L
V2 = 5.00L
T1 = 263K
T2 = 313K

Am I to assume that pressure is at 1 atm? 

[Nobby]

use  pV = nRT

[DevaDevil]

the change in pressure can be expressed as: delta p = p₂ - p₁

what you CAN calculate is the ratio of P2/P1, which means you can express the delta p in terms of increase/decrease of x times the original volume: delta p = x * p₁

Nobby: pV = nRT does NOT work, as you do not have the original pressure, NOR the number of moles

[Nobby]

It will guide to your equation.

pV = nRT

P₁V₁ = nRT₁

P₂V₂ = nRT₂

nR = const.

p₁V₁/T₁ = p₂V₂/T₂

p₁ = P₂*(V₂*T₁)/(V₁*T₂)

x = (V₂*T₁)/(V₁*T₂)

p₁ = x *p₂

[billnotgatez]

Am I missing something here
Why not use 1 ATM for the initial and then in your answer just say the the final pressure is the calculated final pressure times the intitial.

[Nobby]

Because the pressure is not given, why it should be 1 atm. It could be any pressure times the initial.

[rabolisk]

You can't find  :delta: P. You can only find P2/P1, which, I suppose, is a measure of change in pressure, but not EXACTLY  :delta: P.

[ch3mgirl]

Thank you everyone!